The present invention relates to an information read/write apparatus with an information storage medium mounted thereto, on which information (data) can be read or recorded repeatedly. More particularly, the present invention relates to defragmentation of the information read/write apparatus mounted on a vehicular mobile body such as motor vehicles or trains.
In general, information storage media (hereinafter referred to as storage media) on which information (data) can be read or recorded repeatedly include the HDD (Hard Disc Drive), FD (Floppy Disc), MD (Mini-Disc), MO (Magneto Optical), and CD-RW (Compact Disc ReWritable).
For example, the HDD rotates a stack of several discs at high speeds, the surfaces of which are coated with magnetic material and which are arranged cylindrically, and allows the HDC (Hard Disc Controller) to position the magnetic head over the appropriate area of the discs in a non-contact state. The disc is physically formatted for the purpose of recording data thereon and provided with a number of concentric tracks, with each track being numbered. In addition, each of the tracks is divided into a plurality of sectors, each sector being an area of the minimum size for reading and recording data and provided with a sector number. Moreover, a cylinder on which tracks of the same track number are arranged in the shape of the cylinder is given a cylinder number. A combination of these numbers can determine the physical address indicating the location of data. The HDC positions the magnetic head over the sector of the desired physical address to read or record data.
Such a storage medium has been widely used in personal computers as storage media for the management of information. Recently, the storage medium has started being mounted as memory means to a vehicle-mounted information read/write apparatus, such as an audio-visual apparatus or a GPS (Global Positioning System), which is incorporated into a vehicle such as a motor vehicle to cope with an increase in capacity and a decrease in size and cost of the memory means.
Incidentally, upon recording data on a storage medium like the HDD, vacant sectors are searched to be allocated to store data therein in sequence. Thus, such data which exceeds the minimum size of the sector cannot be accommodated in contiguous regions and may be stored in several non-adjacent sectors at various locations of the disc. The repetition of writing data or deleting data files on the disc has resulted in these non-adjacent sectors. Data files to be read from or data to be written onto the disc has to be physically fragmented. As data files increases in number, it takes longer time for the HDD to access the data files. Therefore, the information read/write apparatus is adapted to rearrange fragmented data files on the storage medium. That is, defragmentation of data files is carried out by which the recorded data files are rearranged such that one data file is placed in contiguous sectors in sequence, thereby improving access speeds to provide efficient reading of data files.
However, an user using a conventional information read/write apparatus mounted on a mobile body may carry out the defragmentation of the storage medium during the movement of the mobile body. In this case, running or mechanical vibration of the mobile body may have adverse effect on the storage medium being defragmented. This may lead to a problem of causing an error to occur upon rearrangement of the order of fragmented recorded data files.
In this context, the present invention was developed to solve the aforementioned problems encountered by the conventional information read/write apparatus. The first aspect of the present invention has an object of providing an information read/write apparatus which can determine the condition under which defragmentation can be performed without causing the storage medium to be affected by running or mechanical vibration of the mobile body.
To achieve the object mentioned above, the present invention provides an information read/write apparatus for reading and recording information on an information storage medium, mounted on a mobile body and allowing information to be read and recorded thereon. The information read/write apparatus is characterized by comprising detection means for detecting that the mobile body is at a standstill. The apparatus is also characterized by comprising a control means for controlling reading and recording of information to relocate information stored on the information storage medium from one to another different position on the information storage medium while the mobile body is being detected to be at a standstill in accordance with output of the detection means.
Furthermore, the present invention is characterized in that the control means controls reading and recording of information to relocate information stored on the information storage medium from one to another different position on the information storage medium when the mobile body is detected to be at a standstill for a predetermined length of time or more in accordance with the output from the detection means.
Furthermore, as the second embodiment of the apparatus, the present invention provides the other information read/write apparatus for reading and recording information on an information storage medium, mounted on a mobile body and allowing information to be read and recorded thereon. The information read/write apparatus is characterized by comprising detection means for detecting that the mobile body is at a standstill, read means for reading information on another information storage medium different from the information storage medium, and further control means for controlling a relocation of information stored on another information storage medium different from the information storage medium onto the information storage medium when the mobile body is detected to be at a standstill for a predetermined length of time or more in accordance with output from the detection means.
As described in the foregoing, the information read/write apparatus according to the present invention first confirms positively that the mobile body is at a standstill to perform the defragmentation execution processing on an information storage medium mounted to the storage medium read apparatus. This thereby allows the vibration caused by the movement of the mobile body to have no effect on the information storage medium under the defragmentation execution processing. Thus, errors can be prevented from being generated while the order of the recorded data files fragmented on the information storage medium is being rearranged.
The second aspect of the present invention has an object of providing a method for correcting an information storage position in which a relocation processing is executed on sectors of an information storage medium, mounted on a mobile body and allowing information to be read and recorded thereon, without causing the relocation processing to be affected by running or mechanical vibration of the mobile body.
To achieve the objects mentioned above, the present invention provides the method comprising the following steps, namely, a step of determining that the mobile body is at a standstill, and of controlling reading/recording of information to relocate information stored on the information storage medium from one to another different position on the sector of the information storage medium while the mobile body is being determined to be at a standstill in accordance with output of the determination.
As another embodiment of the above method, the step of controlling to relocate the information may be started when the mobile body is determined to be at a standstill for a predetermined length of time or more in accordance with the output from the determining step.
As the further embodiment of the above method, the method may comprise the steps of detecting whether vehicle speed pulse is present or not, starting the relocation processing when the vehicle speed pulse is not detected, determining whether the relocation processing is completed, detecting again whether the vehicle speed pulse is present or not when not completed, and canceling the relocation processing when the vehicle speed pulse is detected.
As described in the foregoing, the method for correcting an information storage position according to the present invention first confirms positively that the mobile body is at a standstill to perform the defragmentation execution processing on an information storage medium mounted to the storage medium read apparatus. This thereby allows the vibration caused by the movement of the mobile body to have no effect on the information storage medium under the defragmentation execution processing. Thus, errors can be prevented from being generated while the order of the recorded data files fragmented on the information storage medium is being rearranged. In addition, since it is detected on the way again whether the vehicle speed pulse is generated in the last embodiment, even a long time of the relocation processing can be performed without effect of vibration.